This invention is directed to a method and apparatus for handling and cutting sheet or web-type materials, such as broke, on a papermaking machine, by high pressure liquid cutting jets.
For example, in broke handling, when a break occurs somewhere along the line in a papermaking machine, it is necessary to cut the sheet off and divert it for disposal. Typically, the newly formed paper web, at the wet end of the machine, may be broken up or disintegrated by a plurality of transversely positioned, low-pressure showers. Such stripper or shower arrangements for disintegrating a newly formed web as broke material are shown in Moore, U.S. Pat. No. 2,954,082 issued Sep. 27, 1960; Nelson, U.S. Pat. No. 3,245,872 issued Apr. 12, 1966; and Strempel, U.S. Pat. No. 3,097,992 of Jul. 16, 1963. While low pressure knock-off showers have been successfully used at the wet end, they are not used at the dry end of the machine for handling broke due to the substantially increased strength of the paper web after one or more pressing and drying stages.
The prior art shows various broke handling apparatus between or at the end of dryer sections for receiving and sometimes cutting, or mechanically reducing the web before or after it is delivered through a hole in the floor to a basement receiving or conveying system. Thus, Ford, U.S. Pat. No. 3,011,733 issued Dec. 5, 1961 illustrates a broke-receiving hole, otherwise known as a broke hole, for receiving a leading edge of such broke, including apparatus intended to wind the broken web piece upon a temporary storage or cutting drum without further cutting or size reduction.
Corbin et al, U.S. Pat. No. 2,888,073 issued May 29, 1959 describes an arrangement for laterally conveying broke at the press section of a papermaking machine by delivering the paper to one side of the machine without the use of a broke hole. A water jet slitter positioned at the off-running end of the forming wire cuts the green broke as it leaves the wire and before it engages the transverse doctor, for removing the broke from the press section.
Stark, U.S. Pat. No. 2,860,550 issued Nov. 18, 1958 illustrates a mechanical conveyor arrangement by which sheets of broke are delivered from the broke hole to a basement pulper.
Typically, when a break occurs in the press or dryer section, the web is first cut by a flying knife which traverses the web to separate it from the remaining web, and a deflector or doctor blade directs the now cut web toward a broke hole, or otherwise into slitting or conveying apparatus. A partially dried or green web has also been severed by a high pressure water jet arrangement as shown in Grupp, U.S. Pat. No. 4,182,170, where a pair of oppositely positioned water jets are pivotally mounted to move in a cutting direction transverse to the plane of the running web. The jets are moved to make a single cut across the web and to sever the web.
After the broke has been severed, it is desirable to cut it up into smaller pieces to assist in moving the broke out of the way and for further processing. An arrangement for mechanically shredding the broke into smaller chevron-shaped pieces immediately under the broke hole, and for hydraulic delivery to a pulper, is shown in Whiteside, U.S. Pat. No. 3,236,723 issued Feb. 22, 1966. In Whiteside, a rotary toothed cutter operates in conjunction with a bed knife to shred the broke sheet as it is delivered through the broke hole, for subsequent delivery to conveying and re-pulping apparatus.
Broke reducing or comminuting systems have not been widely adopted for handling broke the dryer sections of from board machines. More likely, the board is simply allowed to drop into a pit, or is pulled off to one side of the machine and then handled manually or with a fork lift truck for disposal. The stiffness of the material and its weight often require the application of extreme measures in removing the broke from the floor and disposing of the same.
The present systems of handling broke at the dryer section of a papermaking machine are generally characterized best by cumbersome mechanical apparatus. A need exists for a high speed, lightweight and effective broke cutting and size reducing apparatus and method, for dried or partially dry paper webs.